trace/control-target.c

/*
 * Interface for configuring and controlling the state of tracing events.
 *
 * Copyright (C) 2014-2017 Lluís Vilanova <vilanova@ac.upc.edu>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 */

#include "qemu/osdep.h"
#include "cpu.h"
#include "trace/trace-root.h"
#include "trace/control.h"


void trace_event_set_state_dynamic_init(TraceEvent *ev, bool state)
{
    bool state_pre;
    assert(trace_event_get_state_static(ev));
    /*
     * We ignore the "vcpu" property here, since no vCPUs have been created
     * yet. Then dstate can only be 1 or 0.
     */
    state_pre = *ev->dstate;
    if (state_pre != state) {
        if (state) {
            trace_events_enabled_count++;
            *ev->dstate = 1;
        } else {
            trace_events_enabled_count--;
            *ev->dstate = 0;
        }
    }
}

void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
{
    CPUState *vcpu;
    assert(trace_event_get_state_static(ev));
    if (trace_event_is_vcpu(ev) && likely(first_cpu != NULL)) {
        CPU_FOREACH(vcpu) {
            trace_event_set_vcpu_state_dynamic(vcpu, ev, state);
        }
    } else {
        /*
         * Without the "vcpu" property, dstate can only be 1 or 0. With it, we
         * haven't instantiated any vCPU yet, so we will set a global state
         * instead, and trace_init_vcpu will reconcile it afterwards.
         */
        bool state_pre = *ev->dstate;
        if (state_pre != state) {
            if (state) {
                trace_events_enabled_count++;
                *ev->dstate = 1;
            } else {
                trace_events_enabled_count--;
                *ev->dstate = 0;
            }
        }
    }
}

static void trace_event_synchronize_vcpu_state_dynamic(
    CPUState *vcpu, run_on_cpu_data ignored)
{
    bitmap_copy(vcpu->trace_dstate, vcpu->trace_dstate_delayed,
                CPU_TRACE_DSTATE_MAX_EVENTS);
    cpu_tb_jmp_cache_clear(vcpu);
}

void trace_event_set_vcpu_state_dynamic(CPUState *vcpu,
                                        TraceEvent *ev, bool state)
{
    uint32_t vcpu_id;
    bool state_pre;
    assert(trace_event_get_state_static(ev));
    assert(trace_event_is_vcpu(ev));
    vcpu_id = trace_event_get_vcpu_id(ev);
    state_pre = test_bit(vcpu_id, vcpu->trace_dstate);
    if (state_pre != state) {
        if (state) {
            trace_events_enabled_count++;
            set_bit(vcpu_id, vcpu->trace_dstate_delayed);
            (*ev->dstate)++;
        } else {
            trace_events_enabled_count--;
            clear_bit(vcpu_id, vcpu->trace_dstate_delayed);
            (*ev->dstate)--;
        }
        if (vcpu->created) {
            /*
             * Delay changes until next TB; we want all TBs to be built from a
             * single set of dstate values to ensure consistency of generated
             * tracing code.
             */
            async_run_on_cpu(vcpu, trace_event_synchronize_vcpu_state_dynamic,
                             RUN_ON_CPU_NULL);
        } else {
            trace_event_synchronize_vcpu_state_dynamic(vcpu, RUN_ON_CPU_NULL);
        }
    }
}

static bool adding_first_cpu1(void)
{
    CPUState *cpu;
    size_t count = 0;
    CPU_FOREACH(cpu) {
        count++;
        if (count > 1) {
            return false;
        }
    }
    return true;
}

static bool adding_first_cpu(void)
{
    bool res;
    cpu_list_lock();
    res = adding_first_cpu1();
    cpu_list_unlock();
    return res;
}

void trace_init_vcpu(CPUState *vcpu)
{
    TraceEventIter iter;
    TraceEvent *ev;
    trace_event_iter_init_all(&iter);
    while ((ev = trace_event_iter_next(&iter)) != NULL) {
        if (trace_event_is_vcpu(ev) &&
            trace_event_get_state_static(ev) &&
            trace_event_get_state_dynamic(ev)) {
            if (adding_first_cpu()) {
                /* check preconditions */
                assert(*ev->dstate == 1);
                /* disable early-init state ... */
                *ev->dstate = 0;
                trace_events_enabled_count--;
                /* ... and properly re-enable */
                trace_event_set_vcpu_state_dynamic(vcpu, ev, true);
            } else {
                trace_event_set_vcpu_state_dynamic(vcpu, ev, true);
            }
        }
    }
    trace_guest_cpu_enter(vcpu);
}